Low-voltage lighting fixture

ABSTRACT

A low-voltage lighting fixture comprises a pair of parallel electrical conductor rails, and an electrical current collector shoe slidingly mounted on the conductor rails. The collector shoe comprises a pair of collector heads slidingly mounted on the rails and a socket carrier electrically conductively connected to the collector heads and comprised of two electrically conductive socket sections electrically insulated from each other by an insulating element positioned between the socket sections. The socket carrier is mounted between the collector heads for rotation about an axis extending perpendicularly to the rails, and there is a socket for a lamp on the socket carrier.

The invention concerns a low-voltage lighting fixture, consisting of apair of parallel conductor rails and a collector shoe which can slidealong the conductor rails and has an insulating feature to preventcurrent from flowing between the two conductor rails, and a swivelingholder for a lamp socket or similar device which is electricallyconnected to the two sliding shoe sections that are electricallyseparated from each other by the insulating feature.

As described by EP-A1 0 171 126, such a low-voltage lighting fixturealready exists in connection with a suspension device for pictures etc.,where two swivel arms which are insulated from each other are joined toa rigid sliding collector shoe and carry a swiveling lamp housingbetween their free ends. The swivel arms serve as an electricallyconducting connection between the individual conductor rails and thelamp housing. Consequently, the design of this lighting fixture isrelatively large and bulky. Morever, it permits swiveling of the lightsource only around an axis at right angles to the collector shoe guides,and also gives rise to frequent contact problems in the hinging areasbetween the sliding shoe and the swivel arms, or between the swivel armsand the lamp socket located inside the lamp housing.

Also, a low-voltage lighting fixture has been proposed according toDE-A-3 151 996 that features a block-shaped collector shoe which canslide along the pair of conductor rails and has a receiving trough and amagnet to receive a lamp with a ball-shaped housing. In this case, theelectrical connection between the sliding collector shoe and the lampmust be provided by a separate cable, and the attachment of the lamp bymeans of magnetic forces remains rather uncertain due to theelectromagnetic fields caused by the frequently high currents oflow-voltage installations. Moreover, the available range of illuminationis quite limited due to the collector block itself, in spite of the factthat the ball-shaped housing can swivel freely inside the receivingtrough.

Therefore, this invention aims to eliminate these drawbacks by creatinga low-voltage lighting fixture of the type described in theintroduction, which stands out due to its space-saving, compact design,its robustness and functional reliability, and above all due to itsability to swivel freely as well as its all-round illumination range.

The invention achieves this objective by providing a sliding collectorshoe consisting of two collector heads located on the rails and a lampsocket carrier situated between the collector heads which can swivelabout an axis at right angles to the direction of the collector shoeguides. The lamp socket carrier is electrically connected to thecollector heads in an articulated manner, is subdivided by means of aninsulating intermediate element, and also is intended to form a carrierand electrical connection for the lamp socket. The lamp socket, or thelamp itself, is therefore mounted directly on the freely rotating centerpart of the socket carrier which forms the sliding collector shoe, andthus can be swiveled as desired between the collector heads. No separateswiveling arms and no cable connections are required, and a compact,sturdy lighting fixture is created in the smallest possible space.

In order to add another dimension to the swiveling range of the lampsocket, a particularly advantageous form of implementation of theinvention provides the socket carrier holding the lamp socket with acarrier arm which is mounted between one of the socket carrier sectionsand a mounting bracket electrically connected to the other socketcarrier section and can swivel about an axis at right angles to therotating axis of the socket carrier. The carrier arm, which is supportedat both ends in an electrically conducting manner, is divided by aninsulating spacer just like the socket carrier, and in turn will carrythe lamp socket. The result is a conductive universal joint that acts asa lamp socket holder, so that the lamp can be pointed in any directionand a practically unlimited area of illumination is achieved.Notwithstanding the ability to swivel freely, space requirements remainminimal, and the self-conducting carrier and arm elements provide acableless electrical connection to the conductor rails and assuretroublefree operation over long periods.

If, as provided by the invention, the socket carrier and--ifapplicable--the carrier arm consist of two metal bushings which areplugged onto both sides of the disk-shaped intermediate element thatforms plug-on tenons, a simple, economical design is achieved which isoptimally suited to its insulating task on the one hand, and to itscurrent-conducting task on the other hand.

It is also advantageous to have a lamp socket formed by a pair ofplug-in pins whose pins are mounted on both sides of the intermediateelement in the two sections of the socket carrier or carrier arm, sincethis results in a particularly economical, space-saving and sturdy lampsocket.

If the plug-in pins in this design protrude radially through the metalbushings into the plug-on tenons of the intermediate element, theseplug-in pins can also serve to fix the intermediate element to the metalbushings, which further simplifies the structure.

In order to achieve a good, low-resistance connection between the partsthat can be rotated with respect to each other, the socket carrier orthe carrier arm can be rotatably attached by placing the metal bushingswith a frontal bearing hole over a metal bearing pin fitted to the partthat supports them, with spring-loading between the supporting part anda pin head by means of a metal spring. This leads to a kind ofself-restraining rotatability of the socket carrier with respect to thecollector heads, or of the carrier arm with respect to the socketcarrier or its supporting bracket, which causes the lamp socket toremain securely positioned in any rotational position. Moreover, thespring-loading of the parts assures proper electrical contact.

The drawing shows the object of the invention schematically, as follows:

FIG. 1 shows a perspective view of a low-voltage lighting fixtureaccording to the invention, and

FIGS. 2 and 3 show partial sections of two implemented examples of thesliding collector shoe of this lighting fixture at different scalefactors.

On a pair of conductor rails 1, which is connected to a low-voltagepower source in a manner not shown by the drawing and can be installedin parallel and insulated from one another in any desired position anddirection by means of rail holders 2, a sliding collector shoe 3 ismounted which makes contact with the conductor rails 1 through collectorheads 4 and can be fixed in any position along the rails by means ofclamping screws 5 that penetrate into the slot- or hole-shaped guideopenings 6 of the collector heads 4. Between the collector heads 4, thecollector shoe 3 is fitted with a socket carrier 7 for the lamp socketof a low-voltage lamp L that can be rotated about a transverse axis Awhich runs at right angles with respect to the guide openings 6. Thesocket carrier is subdivided by an insulating intermediate element 8 andconsists of two metal bushings 7a, 7b placed over the disk-shapedintermediate element which carries plug-on tenons 8a at opposite ends.For attaching the socket carrier 7 to the collector heads 4, each sideis fitted with a bearing pin 10 that protrudes through a frontal bearinghole 9 of the metal bushings 7a, 7b and is seated in the adjoiningcollector head 4. A metal spring 11, confined between the bearing pinhead 10a and the metal bushing 7a, 7b provides tension between the metalbushing 7a, 7b and the collector head 4. This creates a highlyconductive, self-restraining, rotatable attachment of the socket carrier7 to the collector heads 4.

As indicated in FIG. 2, the socket carrier 7 itself can now act as asupport and socket for the low-voltage lamp L, with a pair of plug-interminals 12 being fitted to the metal bushings 7a, 7b of the socketcarrier 7 on either side of the intermediate element 8, the plug-interminals 12 protruding through the metal bushings 7a, 7b and extendinginto the plug-on tenons 8a of the intermediate element 8 in order tosecure the cohesion of the socket carrier 7. Since the plug-in terminals12, due to their position in the metal bushings 7a, 7b connect directlyto the two shoe sections, which are electrically separated by theintermediate element 8, the required power supply of a lamp L insertedinto the plug-in terminals 12 is assured. By sliding the collector shoe3 along the pair of conductor rails 1, this lamp can be positioned asdesired and can be rotated to any direction around the transverse axis Aby turning the socket carrier 7.

In order to achieve a wider swiveling range, the socket carrier 7 can beequipped with a carrier arm 13, as illustrated in FIG. 3, which issupported between one of the metal bushings 7b, or a saddle-shapedextension 7c of the socket carrier 7, and a holding bracket 14 attachedto the other metal bushing 7a and can be rotated about an axis B atright angles to the transverse axis A, and consists of two metalbushings 13a, 13b and an insulating intermediate element 15, similar tothe socket carrier 7. Here, as well, an electrically conductive,rotatable attachment is achieved by bearing pins 10 and springs 11 totension the rotatable parts relative to each other. The pair of plug-interminals 12 forms the lamp socket, with the plug-in terminals 12 againprotruding into the interior of the metal bushings 13a, 13b andextending into the plug-on tenons 15a of the intermediate element 15.This results in a lighting fixture with a lamp which can not only belongitudinally positioned along the pair of rails 1 and can be swiveledabout a transverse axis A, but can also be rotated about an axis B atright angles to A, so that in practice an all-round range ofillumination becomes available.

What is claimed is:
 1. A low-voltage lighting fixture comprising(a) a pair of parallel electrical conductor rails, and (b) an electrical current collector shoe slidingly mounted on the conductor rails, the collector shoe comprising(1) a pair of collector heads slidingly mounted on the rails, (2) a socket carrier electrically conductively connected to the collector heads and comprised of two electrically conductive socket carrier sections electrically insulated from each other by an insulating element positioned between the socket sections, (3) means for mounting the socket carrier between the collector heads for rotation about an axis extending perpendicularly to the rails, and (4) means forming a socket for a lamp on the socket carrier.
 2. The low-voltage lighting fixture of claim 1, where in the means for forming a socket comprises a carrier arm, the carrier arm being comprised of two electrically conductive carrier arm sections electrically insulated from each other by an insulating element positioned between the carrier arm sections, and further comprising a holding bracket connected between one of the socket sections and the carrier arm, and means for mounting the carrier arm on the other socket section for rotation about an axis extending perpendicularly to the axis of rotation of the socket carrier.
 3. The low-voltage lighting fixture of claim 2, wherein the socket carrier sections and carrier arm sections are metal bushings, and the insulating elements are disc-shaped insulations having plug-on tenons receiving the bushings.
 4. The low-voltage lighting fixture of claim 3, wherein the means for mounting the socket carrier for rotation comprises respective metallic bearing pins passing through bearing holes in outer ends of the metal bushings and supporting the metal bushings on the collector heads, the bearing pins having heads, and a metallic spring between each bearing pin head and collector head clamping each metal bushing in position.
 5. The low-voltage lighting fixture of claim 3, wherein the means for mounting the carrier arm for rotation comprises respective metallic bearing pins passing through bearing holes in outer ends of the metal bushings of the carrier arm section and supporting said metal bushings on the holding bracket and the other section, respectively, the bearing pins having heads, and a metallic spring between each bearing pin head and the other socket section and holding bracket, respectively, for clamping each metal bushing in position.
 6. The low-voltage lighting fixture of claim 2, wherein the means forming a lamp socket is comprised of a pair of plug-in terminals, a respective one of the terminals being mounted on each carrier arm section adjacent the insulating element.
 7. The low-voltage lighting fixture of claim 2, wherein the socket carrier sections and carrier arm sections are metal bushings, the insulating elements are disc-shaped insulations having plug-on tenons receiving the bushings, the means forming a lamp socket is comprised of said carrier arm including a pair of plug-in terminals, and a respective one of the terminals is mounted on each carrier arm section adjacent the insulating element and extends radially inwardly into the plug-on tenon of the adjacent insulating element.
 8. The low-voltage lighting fixture of claim 1, wherein the means forming a lamp socket is comprised of a pair of plug-in terminals, a respective one of the terminals being mounted on each socket carrier section adjacent the insulating element. 